| A total of 234 surface soil samples (0-20 cm) were collected at the nodes of a 2×2 km grid from Gaoqing County (a typical area surrounding the Lower Yellow River) and analyzed for eight heavy metals (As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn). This study investigated the source of the heavy metals in this area based on a correlation analysis, PCA, and ANOVA using multivariate statistical analysis. In addition, the spatial variation and distribution characteristics of the heavy metals were determined by geostatistics based on GIS. The results provided the following conclusions. ① The mean concentrations of As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn exceeded the background values (BV) of the Lower Yellow River, especially for As, Cu, and Hg (1.23, 1.20 and 1.29 times the BV, respectively), indicating that there was enrichment of the heavy metals in soils at different degrees. ② The results from the multivariate analysis suggested that all eight heavy metals could be classified by two principal components (PCs). The levels of As, Cd, Cr, Cu, Ni, Pb, and Zn were dominated by human activities and the parent soil material (PC1). However, Hg originated mainly from textile printing, petrochemical engineering, and plastic processing (PC2). ③ The differences in heavy metal contents between different land use types and parent soil materials were obvious. The eight elements were highest in land related to urban construction. In addition to Hg, the remaining seven heavy metals were highest in soils in the lacustrine deposit. ④ The spatial distributions of the heavy metals in the soil were different. The high value areas of As, Cd, Cr, Cu, Ni, Pb, and Zn were mainly concentrated in the central urban and southeastern areas, while the high value areas for Hg were concentrated in the southwestern and northeastern areas. This showed that industrial emissions and agricultural production activities caused the degree of heavy metal pollution in the soils while traffic emissions aggravated the levels. |
